The invention is directed to a laser arrangement having at least one laser resonator and a passive resonator coupled thereto.
Semiconductor laser arrangements that oscillate in only one mode are known from the literature (see, for example, B. R. Plastow et al, 9th IEEE ISLC, Rio de Janeiro, Aug. 1984, pages 72 ff; Z. L. Liau et al, Appl. Phys. Lett. 46 (1985), pages 115 ff; M. Ohshima et al, 9th IEEE ISLC. Rio de Janeiro, Aug. 1984, pages 188 ff; H. K. Choi et al, Elec. Lett. 19 (1983) pages 302 ff; L. A. Coldren et al, Appl. Phys. Lett. 46 (1985) pages 5 ff). These arrangements contain a plurality of laser-active and laser-passive Fabry-Perot resonators that are longitudinally coupled. The various arrangements differ in terms of their coupling elements. In "cleaved coupled cavity" lasers and "groove-coupled cavity" lasers, an air gap having plane-parallel mirror surfaces is employed as coupling element between two active laser resonators having differing optical length (see, for example, L. A. Coldren et al, Appl. Phys. Lett. Volume 46 (1985), pages 5 ff). In the "active-passive interference" laser, a passive resonator is longitudinally coupled to an active laser resonator via a step in a wave guide structure (see, for example, H. K. Choi and S. Wang, Elec. Lett. Volume 19 (1983) pages 302 ff). In the "internal reflection interference" laser, the coupling ensues via a disturbance of the refractive index that is built into the wave guide (M. Oshima et al, 9th IEEE ISLC, Rio de Janeiro, Aug. 1984, pages 188 ff).
These coupling elements lead to a pronounced and frequency-dependent coupling. Excessive couplings lead to a de stabilization of the operating point of the laser. Great frequency dependency of the coupling leads thereto that abrupt discontinuities of the resonant frequency occur given slight temperature or, respectively, current fluctuations.